The exemplary embodiments relate to a fabricated structure. It finds particular application in electrostatic extraction of pigments from a liquid ink for marking, and will be described with particular reference thereto. However, it is to be appreciated that the present exemplary embodiments are also amenable to other like applications.
Digital printing processes using liquid inks with suspended particles have been developed for high quality and high speed printing targeted in commercial and industrial markets. However, at this time, some print head fabrication schemes do not lend themselves to batch fabrication and excellent printing characteristics. A planar batch-fabricated process would be particularly beneficial. The technology demands well defined electrostatic field concentrators (tips) that can be precisely and uniformly positioned relative to each other. Preferably, tips would have internal structures and overall shapes to optimize capillary and electrostatic forces.
FIGS. 1A and 1B schematically illustrate a known system 100 for pigment extraction from an electrically insulating liquid. A conducting nib or tip 102 extending slightly above the flowing liquid reservoir 104 is coated with liquid 106 by capillary forces. Positively charged pigment particles 108 (Illustrated in FIG. 1B) are suspended within the fluid. A positive pulse 110 applied to the nib 102 propels the pigment particles toward the ‘ground electrode’ 114 which extracts the concentrated particles in a droplet from the nib or tip 102.
In addition, other structures known as CLAW structures have found use in photo-lithographically patterned spring structures. U.S. Pat. No. 6,794,737 B2 to Fork et al., and U.S. Pat. No. 5,613,861 A to Smith et al., both disclose a stress-balancing layer formed over portions of a self-lifting spring finger that remain attached to an underlying substrate to counter internal stress. These structures are based on depositing and patterning metal layers with controlled vertical stress gradients. Upon release the metal strips curl up out of the plane of fabrication. Additional layers are formed by various methods such as sputtering, plating, etc. and combinations, thereof.